lucene-java-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Benson Margulies <ben...@basistech.com>
Subject Re: LookaheadTokenFilter
Date Sat, 07 Sep 2013 19:40:33 GMT
I think I had better build you a test case for this situation, and
attach it to a JIRA.

On Sat, Sep 7, 2013 at 3:33 PM, Michael McCandless
<lucene@mikemccandless.com> wrote:
> Something is wrong; I'm not sure what offhand, but calling peekToken
> 10 times should not stack all tokens @ position 0; it should stack the
> tokens at the positions where they occurred.  Are you sure the posIncr
> att is sometimes 1 (i.e., the position is in fact moving forward for
> some tokens)?
>
> nextToken() only calls peekToken() once the lookahead buffer is exhausted.
>
> afterPosition() should be called within nextToken(), for each
> position, once all tokens leaving that position are done.
>
> You use case *should* be working: inside your incrementToken() you
> call peekToken() over and over until you've seen the full sentence
> (saving away any state in your subclass of Position), then nextToken()
> to emit the buffered tokens, and to insert your own tokens when
> afterPosition() is called ...
>
> Mike McCandless
>
> http://blog.mikemccandless.com
>
>
> On Sat, Sep 7, 2013 at 1:10 PM, Benson Margulies <benson@basistech.com> wrote:
>> nextToken() calls peekToken(). That seems to prevent my lookahead
>> processing from seeing that item later. Am I missing something?
>>
>>
>> On Fri, Sep 6, 2013 at 9:15 PM, Benson Margulies <benson@basistech.com> wrote:
>>> I think that the penny just dropped, and I should not be using this class.
>>>
>>> If I call peekToken 10 times while sitting at token 0, this class will
>>> stack up all 10 of these _at token position 0_. That's not really very
>>> helpful for what I'm doing. I need to borrow code from this class and
>>> not use it.
>>>
>>> On Fri, Sep 6, 2013 at 9:10 PM, Benson Margulies <benson@basistech.com>
wrote:
>>>> Michael,
>>>>
>>>> I'm apparently not fully deconfused yet.
>>>>
>>>> I've got a very simple incrementToken function. It calls peekToken to
>>>> stack up the tokens.
>>>>
>>>> afterPosition is never called; I expected it to be called as each of
>>>> the peeked tokens gets next-ed back out.
>>>>
>>>> I assume that I'm missing something simple.
>>>>
>>>>
>>>>     public boolean incrementToken() throws IOException {
>>>>         if (positions.getMaxPos() < 0) {
>>>>             peekSentence();
>>>>         }
>>>>         return nextToken();
>>>>     }
>>>>
>>>>
>>>>
>>>> On Fri, Sep 6, 2013 at 8:13 AM, Benson Margulies <benson@basistech.com>
wrote:
>>>>> On Fri, Sep 6, 2013 at 7:31 AM, Michael McCandless
>>>>> <lucene@mikemccandless.com> wrote:
>>>>>>
>>>>>> On Thu, Sep 5, 2013 at 8:44 PM, Benson Margulies <benson@basistech.com>
wrote:
>>>>>> > I'm trying to work through the logic of reading ahead until
I've seen
>>>>>> > marker for the end of a sentence, then applying some analysis
to all of the
>>>>>> > tokens of the sentence, and then changing some attributes of
each token to
>>>>>> > reflect the results.
>>>>>> >
>>>>>> > The queue of tokens for a position is just a State, so there
isn't an API
>>>>>> > there to set any values.
>>>>>> >
>>>>>> > So do I need to subclass Position for myself, store the additional
>>>>>> > information in there, and set the attributes as each token comes
by on the
>>>>>> > output side?
>>>>>>
>>>>>> Yes, that sounds right.  Either that or, on emitting the eventual
>>>>>> Tokens, apply your logic there (because at that point, after
>>>>>> restoreState, you have access to all the attr values for that token).
>>>>>>
>>>>>> > I would be grateful for a bit more explanation of afterPosition
versus
>>>>>> > incrementToken; some of the mock classes call peek from afterPosition,
and
>>>>>> > I expected to see peek called in incrementToken based on the
javadoc.
>>>>>>
>>>>>> afterPosition is where your subclass can "insert" new tokens.
>>>>>>
>>>>>> I think (it's been a while here...) you are allowed to call peekToken
>>>>>> in afterPosition; this is necessary if your logic about inserting
>>>>>> additional tokens leaving a given position depends on future tokens.
>>>>>>
>>>>>> But: are you doing any new token insertion?  Or are you just tweaking
>>>>>> the attributes of the tokens that pass through the filter?  If it's
>>>>>> the latter then this class may be overkill ... you could make a simple
>>>>>> TokenFilter.incrementToken that just enumerates & saves all input
>>>>>> tokens, does its processing, then returns those tokens one by one,
>>>>>> instead.
>>>>>
>>>>> I'm not adding tokens yet, but I will be soon, so all of this isn't
>>>>> entirely crazy. The underlying capability here includes decompounding.
>>>>> (I have mixed feelings about just adding all the fragments to the
>>>>> token stream, as it can reduce precision, but there isn't an obvious
>>>>> alternative (except perhaps to suppress the super-common ones)).
>>>>>
>>>>> So, to summarize, logic might be:
>>>>>
>>>>> in incrementToken:
>>>>>
>>>>> If positions.getMaxPos() > -1. just return nextToken(). If not, loop
>>>>> calling peekToken to acquire a sentence, process the sentence, and
>>>>> attach the lemmas and compound-pieces to the Position subclass
>>>>> objects.
>>>>>
>>>>> in afterPosition, as each token comes 'into focus', splat the lemma
>>>>> from the Position into the char term attribute, and insert new tokens
>>>>> as needed for the compound components.
>>>>>
>>>>> Thanks,
>>>>> benson
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>
>>>>>>
>>>>>> Mike McCandless
>>>>>>
>>>>>> http://blog.mikemccandless.com
>>>>>>
>>>>>> ---------------------------------------------------------------------
>>>>>> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
>>>>>> For additional commands, e-mail: java-user-help@lucene.apache.org
>>>>>>
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
>> For additional commands, e-mail: java-user-help@lucene.apache.org
>>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> For additional commands, e-mail: java-user-help@lucene.apache.org
>

---------------------------------------------------------------------
To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
For additional commands, e-mail: java-user-help@lucene.apache.org


Mime
View raw message